Axial, cylindrical component connectors of many types are in use today for forming mechanical connections between mating electrical contacts, hose connections or conduit connections for fluid systems, or tubular connectors for connecting componentry of optical or optical electrical circuits. In aerospace and military applications, the most common electrical connector is the bayonet coupled, cylindrical connector. This connector uses a bayonet coupling ring, wherein three circumferentially spaced cam grooves inside the rotary coupling ring, on the plug half, engage three bayonet pins secured to or projecting from the circumference of the receptacle to advance the plug half into the receptacle, when the coupling ring is rotated. While this provides very rapid engagement and disengagement of the plug relative to the receptacle, the ends of the cam grooves must necessarily include detents to prevent the bayonet pins from backing down the ramps defined by the cam grooves, and the coupling ring thus requires a spring to bias and hold the bayonet pins within the detents. The spring also accommodates the manufacturing tolerances in the receptacle, plug shell and coupling ring. Thus, the plug shell or body is held in the receptacle of tubular form by a spring rather than being firmly locked to the receptacle and prevented from axial and transverse movement.
The U.S. Pat. No. for the bayonet coupled electrical connector 2,984,611-May 16, 1961 to Hennessey et al, describes a mated condition of a plug and receptacle such that the external shoulder on the plug shell is butted against the nose of the receptacle while at the same time the plug insert is in face-to-face sealing with the receptacle insert. The fact is that over the years the interfacial sealing has become an overriding consideration, and now an elastomeric seal is employed between the two inserts, preventing the abutment of the plug shell shoulder against the nose of the receptacle. This essentially causes the plug shell to be suspended between two springs, that is, between the springiness of the elastomeric seal at the face of the plug insert and the wave spring behind the plug shell shoulder. There is, therefore, considerable relative motion possible between the plug shell and the receptacle.
The spring held plug shell approach, while being satisfactory in many applications, is not adequate in environments of very high vibration and shock or in moderate vibration over a long duration. In a space launch vehicle program, a problem of electrical failures was encountered with bayonet coupled connectors during the qualification testing of devices that employ bayonet coupled connectors. The devices were the electro-explosive separation nuts used on the Titan III launch vehicle at the stage 0 to 1, 1 to 2 and 2 to 3 separation interfaces. The qualification tests included subjecting ten separation nuts including the mating electrical connector plugs to extreme mechanical shock and random vibration environments. After completion of the environmental tests, it was found that several the electrical pin male contacts in the connectors were broken and there was severe damage to the plug coupling ring and the receptacle bayonet pins.
Failure analysis of the connectors concluded that the broken electrical pins, and the damage, were caused by the relative motion that occurred between the plug shell and the receptacle during the application of the shock and random vibration environments. It was further determined that the spring member would have to be removed from the coupling ring design and that the plug body would have to be rigidly connected to the receptacle in order for the connectors to survive the extreme environments.
There are approximately five hundred wired and potted separation nut connector plugs that have already been installed and electrically tested on existing Titan IIIC and IIID launch vehicles. There is a need for replacement coupling rings, or else the entire connector plugs will have to be cut off and replaced and retested.
There is another very strong trend in this electronics age towards the insuring of electrical grounding between electrical connector plugs and their mating receptacles. This is necessary because as the electrical circuits become more and more complex, the RFI or EMC shielding protection becomes more compelling. Because of the relative motion allowable between the plug shell and the receptacle in the spring loaded bayonet coupled connector, the common method of electrically grounding the plug shell to the receptacle in these connectors is by adding a ring of electrically conductive spring fingers in between the plug shell and the receptacle. The ring of spring fingers is installed in a groove on the outer cylindrical nose portion of the plug shell. After the plug shell nose enters the receptacle, the spring fingers also enter the receptacle, and wipe against the inner wall of the receptacle as the mating is completed. Because the spring fingers are so fragile, and because the inner wall of the receptacle contains keyways, there are many problems associated with the spring finger method of grounding. There is a need for a more rugged, reliable, and less expensive means of grounding plug shells to receptacles.
There are a number of new connectors being offered today. Some are supposed improvements to the bayonet coupled connector, and some include entirely different coupling mechanisms. None of the improved bayonet coupled connectors include true metal to metal locking of the plug shell to the receptacle, and most are not useable on existing plug shells. The new coupling mechanisms require complete changeover of both the plugs and the receptacles. This proliferation is greatly increasing the cost to the military and to the air lines for provisioning the many different connectors.
It is, therefore, a primary object of this invention to provide a bayonet coupling ring for mating connector plugs to receptacles, in which; the coupling ring does not employ a spring member, is intermateable with existing bayonet receptacles; is usable with existing bayonet coupled connector plug shells; positively locks the plug shell metal-to-metal to the receptacle and positively electrically grounds the plug shell to the receptacle.
It is a further object of the present invention to provide a replaceable coupling ring for a conventional bayonet coupled electrical connector plug and receptacle which combines rapid mechanical assist engagement with a final, secure lock up of the plug to the receptacle and which may be readily applied to existing, wired plug shells in place of the conventional coupling rings.